A thermoplastic polyurethane (hereinafter, which may be abbreviated as TPU) is used in various fields, such as various elastomer molded products, synthetic leathers, artificial leathers, adhesive agents, shoe soles, spandexes, or the like. The TPU is prepared by reacting a polyol with an organic polyisocyanate, and a chain extender as needed (Patent Document 3, Patent Document 4, or the like). TPUs having various characteristics can be obtained by changing kinds of a polyol and an organic diisocyanate to be used as raw materials.
Patent Document 1 discloses a transparent hardened sheet obtained by reacting a diphenylmethane diisocyanate with a block copolymer composed of a block formed by a hydrocarbon-based polymer, the main chain of which being approximately saturated and a block formed by conducting ring-opening polymerization of an ε-caprolactone. Patent Document 2 discloses a lactone polymer obtained by conducting ring-opening polymerization of lactones using a polybutadiene polyol as an initiator. Patent Document 2 discloses that the lactone polymer may be used in a thermoplastic urethane elastomer, a thermosetting urethane elastomer, a urethane foam, an adhesive agent, a sealant, a paint, or the like.